Requirement # 1
Based on the completed Helicopter Systems Engineering table for Version B, as shown in the Appendix 1, and given the following budget systems engineering allocation:
- A total capability index of 950
- A total development cost of £400 million
- A unit manufacturing cost of £26 million
- A development timescale of 36 months
- A reliability improvement timescale of 36 months
- An MTBF of 190 flying hours
- A maintainability characteristic of 6.80 maintenance hours per flying hour
- A total maintenance cost of £1,400 million for the total fleet of 50 aircrafts for a life cycle of 30 years
- A total life cycle cost of £3,100 million for the total fleet of 50 aircrafts for a life cycle of 30 years
I proposed the following combination of systems for the helicopter, which I believe is the best combination (please see Appendix 2): Read more at: http://www.essaywriter.co.uk/helicopter-systems-engineering.aspx?id=b4QlIICKDA1tv
- Fuselage A
- Engine B
- Rotor Head Gearbox B
- Combat System B
- Avionic Suite A
In choosing the above combination, I used the following criteria:
2. Next is the development timescale of 36 months. This criteria, I believe, is the next most important as longer development timeframes can result to excess costs of continuing to operate a fleet comprised of old aircraft.
3. Next is the mean time between failures. This MTBF of the systems combination should not be less than the allowable budget of 190 flying hours.
The current systems were not included in the proposed evaluation because of the probability that critical spare parts, when needed, might not be available because of the age of the current systems. Moreover, the capability indices of the current systems are the lowest.
Hence, the total maintenance cost and total life cycle cost are presented below.
A total maintenance cost of £1,492 million which is more than the budget by £92 million or 6.58 per cent.
Total Life Cycle Cost
A total life cycle cost of £3,217 million which is £117 million more than the budget or 3.78 per cent higher. In order to arrive at the above systems combinations and costs, the following trade offs were made:
- A reliability improvement timescale of 48 months in exchange of a development time of 36 months. The tradeoff is based on the relative importance of these two dimensions.
- Putting a higher weight on the development timescale also results to a higher capability index which is 920 and longer mean time between failures, which translates to lower maintainability than if the budget SE allocation for the reliability
- The highest possible capability index was traded off with a lower one in order to meet the development timescale and a lower deviation in the total budget SE allocation for the development cost. A higher capability index means higher development costs for this case.
improvement timescale of 36 months was followed, for the proposed systems combination.
Requirement # 2
The following simplifying assumptions are analysed in terms of their impact on the calculations:
- The most important simplifying assumptions are:
- the in service date of no more than 36 months. This assumption served as a check for the systems chosen as part of the proposed combination
- the average usage of 1,250 flying hours per aircraft per year. Given this assumption, calculating the total maintenance and total lifecycle costs because easier.
- The maintenance man-hour rates and materials. Calculating the TMC and LCC would have a very complex procedure without this simplified assumption.
- A more realistic assumption on total maintenance man-hour rates for fuselage, engine and gearbox, combat and avionic systems, and materials can significantly affect the proposed systems combinations. A simplifying assumption that these costs remain stable over the in-service lifetime of the fleet is far from the real world. It is highly probable that these costs will follow an increasing trend throughout the life of the aircrafts as a result of the interaction of several factors including inflation, obsolescence of the aircrafts themselves and their parts, shortage of the maintenance skills needed. Economists had widely acknowledged the impact of inflation on prices and costs over time (Aggarwal, Harrington, Kobor & Peterson 2008).
- Moreover, the assumption that risks resulting from outsourcing the different materials and systems from different suppliers have no impact on some of the dimensions such as development and reliability improvement timescales is also not parallel with the real world. Numerous suppliers mean a complex project management system for the helicopter’s systems engineering. This complexity translates to different risks not factored in to the simplified assumptions.
Requirement # 3
As a member of the System’s Engineering team, with a focus on achieving the target RAM performance in service, the following are my recommendations needed to ensure that the contractors achieve their RAM performance level targets.
First, the RAM claims made by the contractors regarding their component products have to be quantified. This quantification would enable the company to design specific measurements and criteria in the evaluation of the contractors’ products’ RAM performance in service.
Consequently, the reliability, availability and maintainability contract for each of the different life cycles has to include specific provisions on the contractors’ liabilities whenever the RAM performance in service of their products or components fall below the identified RAM performance level targets.
Moreover, an emphasis of the components’ availability whenever and wherever needed should be stressed in the RAM contract specifically during the first stages of the aircraft’s life cycle. This is to ensure that any deviation in the RAM performance level targets of components can be corrected immediately so as not to jeopardise the RAM of the entire aircraft or fleet.
Requirement # 4
Reliability is defined mathematically as the conditional probability that components, equipment, and systems will perform their intended design functions without failure (August 1999). Therefore, the reliability engineer’s function is to predict the aircraft’s overall reliability and applies engineering methods which ensure that the ‘as designed’ reliability of the aircrafts are achieved or realised. Furthermore, the reliability engineer allocates and assigns reliabilities to the different aircraft components and identifies probable faults for each component. As such, the newly designed and manufactured aircrafts can have higher chance of achieving their ‘as designed’ reliabilities. During the in-service period, the allocation of unreliabilies to the aircraft and its components, the reliability engineers, aircrafts operators and maintainers can be efficient and effective in identifying “areas with the greatest opportunity for improvements” (Eti, Ogaji & Probert 2007, p. 202) and hence, resources are allocated optimally.
To ensure that the helicopters’ “as designed” reliability is realised during their in service life, the following are my main recommendations on management actions and measures to ensure such. These recommendations were designed given that the in-service aircraft operators and maintainers do the job.
First, there is a need for management to establish operating processes, procedures and guidelines, for the three distinct phases of a helicopter’s failure characteristics as identified in the figure in the next page.
Specifically, failures during Phase 1 need to be thoroughly studied to determine the cause of the failure – breakdown in the manufacturing process, component variation or materials deviation. The resolution of the failure depends mainly on what caused it in the first place. Moreover, unless the cause is properly identified and resolved, failures resulting from the same cause will recur all through out Phases 2 and 3.
Second, management needs to ensure that the skills necessary to maintain the helicopters in Phases 1, 2 and 3. As a result of the different and distinct causes of failures in each of the phases, the in-service aircraft operators and maintainers have to be trained and their skills developed for all of the three phases. These skills should be present whenever needed; otherwise the “as designed” reliability of the aircrafts will be compromised if the company’s in-service aircraft operators and maintainers are not equipped to maintain the aircrafts. During the operating and support life cycle of the aircrafts, sources of unreliability have to be identified and traced back to their root causes which can be one of the following: poor design, incorrect operation, inadequate maintenance or a combination thereof (August 1999).
Third, tools, methods and models in reliability, availability, maintainability and supportability of the aircrafts have to be identified to be able for the aircraft operators and maintainers to assess RAM. These tools, methods and models can also be sued before the aircrafts are put into service – they can be used to apply risk analysis during the each of the life cycles of the helicopter’s development (Eti, Ogaji & Probert 2007, p. 205). Some of these RAM tools are the failure-mode effect criticality analysis or FMECA, fault tree analysis of FTA and event tree analysis or ETA. According to Eti, Ogaji and Probert (2007), “[t]he routines for integrating such assessments in the earlier phases of maintenance-planning processes are important in reducing costs and increasing both availability and reliability” (p. 206).
Fourth, as opposed to the tools, methods and models which were focused on the reliability of the aircraft as a whole in the previous recommendation, this recommendation deals with the tools, methods and models on the failure characteristics of the repairable components of the aircraft. For each of the repairable components, a rate of occurrence of failures has to be established to aide the in-service aircraft operators and maintainers in maintaining the fleet.
Fifth, I recommend that a pilot test for each type of failures in each of the different phases be conducted regularly. This is to ensure that the current tools, models, methods, processes, procedures and guidelines are still applicable. Moreover, this can also serve as a further training ground for the aircraft operators and maintainers especially during the early life cycle of the fleet – wherein failures and deviations in the ‘as designed’ reliability performance level targets are fewer than during the later parts of the fleet’s life cycle.
Lastly, the measures that the management adopts must have the following specific objectives:
- Identification of aircrafts or components which have reliabilities or availabilities below those desired to enable the timely and efficient removal of weaknesses or faults in the fleet as a whole and in the aircrafts individually.
- Establish procedures for timely identification of aircrafts or components with excessive failure rates, long repair times or high degrees of uncertainty. Again, this would enable the timely and efficient removal of weaknesses or faults in the fleet as a whole and in the aircrafts individually.
- Establish logistics system to ensure the availability of material components.
According to Eti, Ogaji & Probert (2007) “[m]aintainability analysis has been used to evaluate the design and lay-out with respect to maintenance procedures, and resources. On the basis of the potential impact on plant availability, a spare-part list may be determined and stores kept accordingly. Availability goals can be converted into reliability and maintainability requirements, in terms of acceptable failure rates and outage hours for each component as explicit design-objectives” (p. 221). Hence, in the realisation of the aircraft’s ‘as designed’ reliability, the aircrafts and its component’s availability and maintainability should not be taken separately and independently from their reliability.
In conclusion, management, in implementing the above recommendations, has to realise that reliability is a “fundamental attribute for the safe operation of any modern technological system” (Zio 2009, p. 126) and that any operating processes, procedures and guidelines adopted to increase the chance that the ‘as designed’ reliability of the aircrafts is realised have to factor in the “uncertainty in the failure occurrences and consequences” (Zio 2009, p. 126). These would give the in-service aircraft operators and maintainers the capability to modify the same.